Phosphate ions are usually considered to be responsible for the algal bloom in receiving water bodies and aesthetic problems in water. From the environmental point of view, the management of such contaminant and valua...Phosphate ions are usually considered to be responsible for the algal bloom in receiving water bodies and aesthetic problems in water. From the environmental point of view, the management of such contaminant and valuable resource is very important. The present work deals with the removal of phosphate ions from aqueous solutions using kaolinitic and smectic clay minerals and synthetic zeolite as adsorbent. The pH effect and adsorption kinetic were studied. It was found that phosphate could be efficiently removed at acidic pH （between 4 and 6） and the second order model of kinetics is more adopted for all samples. The isotherms of adsorption of phosphate ions by the two clays and the zeolite samples show that the zeolite has the highest rate of uptake （52.9 mg P/g）. Equilibrium data were well fitted with Langmuir and Freundlich isotherm.展开更多
Carbonate concretions are conspicuous in organic-rich shales and are generally related to decomposition of organic matter.The black shales from the Chang 7 Member of the Upper Triassic Yanchang Formation of the southe...Carbonate concretions are conspicuous in organic-rich shales and are generally related to decomposition of organic matter.The black shales from the Chang 7 Member of the Upper Triassic Yanchang Formation of the southern Ordos Basin host abundant carbonate concretions,which provide a unique record of depositional and early diagenetic conditions of the paleo-lake sediments.However,little attention has been given to the genesis and growth processes of the concretions in these lacustrine petroleum source rocks.New petrographic observations and geochemical analysis show that the concretions are composed of calcite,phosphate fossil fragments,K-NH4-feldspar,quartz,bitumen,and minor Fe-dolomite.Phosphate minerals,mainly carbonate fluorapatite(CFA),show pervasive replacement by calcite,most of which contains phosphorus,ranging in concentration from 0.26 to 2.35 wt%.This suggests that the phosphate minerals are the precursors for concretion growth.Positiveδ13C(+5.6 to+12.4‰V-PDB)signatures and the absence of pyrite indicate that microbial methanogenesis was the dominant driver for concretion growth,rather than bacterial sulfate reduction.Quartz,bitumen,and Fe-dolomite are the last cements that occurred,at deep burial depths and high temperatures.The formation of phosphate minerals might have been induced by upwelling of phosphate-enriched deep water in the Late Triassic paleo-lake,which promoted phytoplankton blooms and further enrichment of organic matter.Extremely slow sedimentation rates of fine-grained detrital minerals,relative to dead organism accumulation,led to the high permeabilities of the organic-rich sediments and rapid concretion growth during shallow burial.The close association of phosphate-bearing carbonate concretions and organic-rich shales reflects that upwelling played a critical role in the formation of the high-quality petroleum source rocks in the Triassic paleo-Ordos lake.展开更多
The under-sampled middle and western branches of Shade River Watershed (SRW) in SE Ohio were investigated as part of the Ohio University—U.S. Environmental Protection Agency (EPA) STAR grant. This project was for mon...The under-sampled middle and western branches of Shade River Watershed (SRW) in SE Ohio were investigated as part of the Ohio University—U.S. Environmental Protection Agency (EPA) STAR grant. This project was for monitoring the quality of watersheds in Ohio and classifying them according to their physical, chemical, and biological conditions. Water samples, as well as field parameters, were taken at twenty-two sites for chemical analyses. The ions analyzed included Ca, Mg, Na, Fe, Mn, Al, NO3, SO4, HCO3, and total PO4, while the field parameters measured included pH, dissolved oxygen (DO), total dissolved solids (TDS), electrical conductivity (EC), and alkalinity. To assess the water quality within the SRW, the analyzed ions and field parameters were compared to the USEPA criteria for the survival of aquatic life. Analytical results showed that the watershed is dominated by Ca-HCO3waters with DO, Fe, Mn, and PO4being the main causes of impairment within the streams. The relatively elevated concentrations of manganese and less extent iron may be associated with the local geology and the acidic nature of the soils. The high alkalinity and calcium concentrations are due to the limestone geology. The elevated phosphate concentration may be due to anthropogenic sources, fertilizers, or contributions from phosphorus-rich bedrock that differs geochemically from other areas.展开更多
The weathering of phosphorus-bearing mineral powder(PBMP) and calcium phosphate(CP) by Aspergillus niger was compared,and the mechanism involved was analyzed for the comprehensive utilization of PBMP.The concentration...The weathering of phosphorus-bearing mineral powder(PBMP) and calcium phosphate(CP) by Aspergillus niger was compared,and the mechanism involved was analyzed for the comprehensive utilization of PBMP.The concentration of water-soluble phosphorus(WSP),Mg2+,and Ca2+at different culture times,microstructures of particles,and mineral compositions was examined by ultraviolet-visible spectrometer(UV),atomic absorption spectrometry(AAS),scanning electron microscopy(SEM),and X-ray diffraction(XRD).Results showed that the change in the concentrations of WSP,Mg2+,and Ca2+were related to the growth of A.niger and the different mineral compositions.Compared with CP,PBMP was weathered harder by fungi.Traces of the weathered mineral were found through SEM.CP not only showed traces of erosion damage but also appeared as a rhombohedron-like substance.The XRD test indicated that the weathering minerals can form water calcium oxalate.Further analysis revealed that the mechanism of PBMP and CP weathering by A.niger was the collaborative result of mycelium biomechanical effects and the acid-soluble role of acidic metabolites.The phosphorus dissolution rate of PBMP after 20 d was 46.83%,whereas that of CP after 12 d was 91.01%.The findings of this study are significant to the effective use of waste PBMP and to the exploitation of low-grade phosphate rock resources.展开更多
文摘Phosphate ions are usually considered to be responsible for the algal bloom in receiving water bodies and aesthetic problems in water. From the environmental point of view, the management of such contaminant and valuable resource is very important. The present work deals with the removal of phosphate ions from aqueous solutions using kaolinitic and smectic clay minerals and synthetic zeolite as adsorbent. The pH effect and adsorption kinetic were studied. It was found that phosphate could be efficiently removed at acidic pH （between 4 and 6） and the second order model of kinetics is more adopted for all samples. The isotherms of adsorption of phosphate ions by the two clays and the zeolite samples show that the zeolite has the highest rate of uptake （52.9 mg P/g）. Equilibrium data were well fitted with Langmuir and Freundlich isotherm.
基金This work was supported by the National Natural Science Foundation of China(Program No.41330315)the Natural Science Foundation of Shaanxi Province(Program No.2020JQ-766)+1 种基金the Scientific Research Program Funded by Shaanxi Provincial Education Department(Program No.20JK0838)the Opening Foundation of Shandong Key Laboratory of Depositional Mineralization&Sedimentary Mineral,Shandong University of Science and Technology(Program No.DMSM20190034).
文摘Carbonate concretions are conspicuous in organic-rich shales and are generally related to decomposition of organic matter.The black shales from the Chang 7 Member of the Upper Triassic Yanchang Formation of the southern Ordos Basin host abundant carbonate concretions,which provide a unique record of depositional and early diagenetic conditions of the paleo-lake sediments.However,little attention has been given to the genesis and growth processes of the concretions in these lacustrine petroleum source rocks.New petrographic observations and geochemical analysis show that the concretions are composed of calcite,phosphate fossil fragments,K-NH4-feldspar,quartz,bitumen,and minor Fe-dolomite.Phosphate minerals,mainly carbonate fluorapatite(CFA),show pervasive replacement by calcite,most of which contains phosphorus,ranging in concentration from 0.26 to 2.35 wt%.This suggests that the phosphate minerals are the precursors for concretion growth.Positiveδ13C(+5.6 to+12.4‰V-PDB)signatures and the absence of pyrite indicate that microbial methanogenesis was the dominant driver for concretion growth,rather than bacterial sulfate reduction.Quartz,bitumen,and Fe-dolomite are the last cements that occurred,at deep burial depths and high temperatures.The formation of phosphate minerals might have been induced by upwelling of phosphate-enriched deep water in the Late Triassic paleo-lake,which promoted phytoplankton blooms and further enrichment of organic matter.Extremely slow sedimentation rates of fine-grained detrital minerals,relative to dead organism accumulation,led to the high permeabilities of the organic-rich sediments and rapid concretion growth during shallow burial.The close association of phosphate-bearing carbonate concretions and organic-rich shales reflects that upwelling played a critical role in the formation of the high-quality petroleum source rocks in the Triassic paleo-Ordos lake.
文摘The under-sampled middle and western branches of Shade River Watershed (SRW) in SE Ohio were investigated as part of the Ohio University—U.S. Environmental Protection Agency (EPA) STAR grant. This project was for monitoring the quality of watersheds in Ohio and classifying them according to their physical, chemical, and biological conditions. Water samples, as well as field parameters, were taken at twenty-two sites for chemical analyses. The ions analyzed included Ca, Mg, Na, Fe, Mn, Al, NO3, SO4, HCO3, and total PO4, while the field parameters measured included pH, dissolved oxygen (DO), total dissolved solids (TDS), electrical conductivity (EC), and alkalinity. To assess the water quality within the SRW, the analyzed ions and field parameters were compared to the USEPA criteria for the survival of aquatic life. Analytical results showed that the watershed is dominated by Ca-HCO3waters with DO, Fe, Mn, and PO4being the main causes of impairment within the streams. The relatively elevated concentrations of manganese and less extent iron may be associated with the local geology and the acidic nature of the soils. The high alkalinity and calcium concentrations are due to the limestone geology. The elevated phosphate concentration may be due to anthropogenic sources, fertilizers, or contributions from phosphorus-rich bedrock that differs geochemically from other areas.
基金the National Natural Science Foundation of China for Creative Research Groups (Grant No. 41021062)the "Hundred Talents" Program of the Chinese Academy of Sciences for their financial support
文摘The weathering of phosphorus-bearing mineral powder(PBMP) and calcium phosphate(CP) by Aspergillus niger was compared,and the mechanism involved was analyzed for the comprehensive utilization of PBMP.The concentration of water-soluble phosphorus(WSP),Mg2+,and Ca2+at different culture times,microstructures of particles,and mineral compositions was examined by ultraviolet-visible spectrometer(UV),atomic absorption spectrometry(AAS),scanning electron microscopy(SEM),and X-ray diffraction(XRD).Results showed that the change in the concentrations of WSP,Mg2+,and Ca2+were related to the growth of A.niger and the different mineral compositions.Compared with CP,PBMP was weathered harder by fungi.Traces of the weathered mineral were found through SEM.CP not only showed traces of erosion damage but also appeared as a rhombohedron-like substance.The XRD test indicated that the weathering minerals can form water calcium oxalate.Further analysis revealed that the mechanism of PBMP and CP weathering by A.niger was the collaborative result of mycelium biomechanical effects and the acid-soluble role of acidic metabolites.The phosphorus dissolution rate of PBMP after 20 d was 46.83%,whereas that of CP after 12 d was 91.01%.The findings of this study are significant to the effective use of waste PBMP and to the exploitation of low-grade phosphate rock resources.
